Effects of fatiguing isometric and isokinetic ankle exercises on postural control while standing on firm and compliant surfaces

Bisson, Remaud Anthony, Boyas Sébastien, Lajoie Yves, Bilodeau, Bilodeau Martin

Description

Fatiguing exercises used across studies to induce alterations in postural control are diverse and may explain the different findings reported. This study aimed to compare the effects of two types of fatiguing plantarflexion exercises on postural control on a firm and a compliant surface. Ten healthy young men (29 ± 4 years) were asked to stand as steadily as possible for 30 s, blindfolded with feet together, on a firm and a compliant surface before and immediately after an isometric and an isokinetic fatiguing exercise. Results Maximal force reduction due to fatigue was found significant but similar between exercises. No significant difference was found between the fatiguing exercises on all Center of Pressure (CoP) parameters. Both fatiguing exercises induced increases in CoP excursion area, CoP variability and CoP velocity in both planes (antero-posterior, mediolateral) on the compliant surface. On the firm surface, both fatiguing exercises only induced increases in CoP variability and CoP velocity in the fatigued plane (antero-posterior). Conclusions Isometric and isokinetic fatiguing exercises, when producing a similar level of force reduction, induce similar decreases in postural control. The effects of fatigue on postural control in healthy young men are more pronounced when standing on a compliant surface, i.e. when proprioceptive information at the ankle is altered.

Sujets

• Posturography
• Center of pressure

Informations

• Publié par: biomed
• Publié le: 01 janvier 2012
• Nombre de lectures: 8
• Langue: English

Extrait

Bissonet al. Journal of NeuroEngineering and Rehabilitation2012,9:39 http://www.jneuroengrehab.com/content/9/1/39

JOURNAL OF NEUROENGINEERING J N E R AND REHABILITATION

R E S E A R C HOpen Access Effects of fatiguing isometric and isokinetic ankle exercises on postural control while standing on firm and compliant surfaces 1,2* 2†1,2†1†1,2,3† Etienne J Bisson, Anthony Remaud, Sébastien Boyas, Yves Lajoieand Martin Bilodeau

Abstract Background:Fatiguing exercises used across studies to induce alterations in postural control are diverse and may explain the different findings reported. This study aimed to compare the effects of two types of fatiguing plantarflexion exercises on postural control on a firm and a compliant surface. Ten healthy young men (29 ± 4 years) were asked to stand as steadily as possible for 30 s, blindfolded with feet together, on a firm and a compliant surface before and immediately after an isometric and an isokinetic fatiguing exercise. Results:Maximal force reduction due to fatigue was found significant but similar between exercises. No significant difference was found between the fatiguing exercises on all Center of Pressure (CoP) parameters. Both fatiguing exercises induced increases in CoP excursion area, CoP variability and CoP velocity in both planes (anteroposterior, mediolateral) on the compliant surface. On the firm surface, both fatiguing exercises only induced increases in CoP variability and CoP velocity in the fatigued plane (anteroposterior). Conclusions:Isometric and isokinetic fatiguing exercises, when producing a similar level of force reduction, induce similar decreases in postural control. The effects of fatigue on postural control in healthy young men are more pronounced when standing on a compliant surface, i.e. when proprioceptive information at the ankle is altered. Keywords:Neuromuscular fatigue, Posturography, Centre of Pressure, Contraction mode, Plantarflexor muscles

Background The ability to perform a multitude of physical activities and most daily living activities requires adequate pos tural control. In order to maintain postural control, the central nervous system must integrate and (re)weigh in formation from the visual, vestibular and somatosensory systems and modulate commands to the neuromuscular system continuously [1]. Not surprisingly, numerous studies [211] have demonstrated an impairment in pos tural control in different postural tasks after neuro muscular fatigue. Since the plantarflexor muscles constitute the main controllers in quiet standing [12], the effect of fatigue of these muscles on postural control

* Correspondence: [e-mail] † Equal contributors 1 School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada 2 Aging and Movement Research Laboratory, Bruyère Research Institute, Ottawa, Canada Full list of author information is available at the end of the article

have been largely examined. The findings, however, vary significantly possibly due to methodological differences (i.e. fatigue protocols, postural stances used and/or amount of visual information available) across studies. In a recent study [4], we found that an isometric fatiguing exercise (standing on tiptoes until exhaustion) increased Center of Pressure (CoP) excursion area, CoP variability and CoP velocity in both anteroposterior (AP) and mediolateral (ML) planes. This increase was found independent of the difficulty of the postural task (unipedal, tandem, bipedal), except for a more pronounced effect for the most challenging postural task (i.e. unipedal stance with eyes closed). Our results were consistent with other studies using a similar isometric fatiguing exercise [5,811]. In contrast, when the ankle musculature was fa tigued with an isokinetic exercise in a different study [2], an increase in CoP velocity was found only in the AP plane, i.e. the plane in which the fatigued plantarflexor muscles act as prime mover muscles. Again, these results were consistent with studies that have used a similar fatiguing

© 2012 Bisson et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.